One of the most common questions asked by people who are looking to buy a thatched property, or who maybe already own a thatched property is “How long will a thatched roof last?”. In this guide, we aim to answer that question by running through 10 things you should take into account when trying to understand how much life is left in a thatched roof.
Contents
- Materials
- Quality of Materials
- Roof Pitch
- The Surrounding Environment
- Pollutants
- Birds, Mice and Other Pests
- Breathability
- Damage
- The Weather
- Quality of Workmanship
1. Materials
The materials making up the roof have a big part to play in ascertaining how much life a thatched roof still has in it. If you’re looking to buy a thatched property, you should ask the sellers when the property was last re-thatched and what material makes up the thatch. If you already own a thatched property, dig out some documentation or get in touch with a qualified Master Thatcher to identify the thatch material.
Once you’ve identified the material that makes up the thatch and you know how long ago since the roof was re-thatched you can begin to get a rough idea of how much life is left in the material itself and therefore start to get an understanding of how long a thatched roof will last.
Water Reed
Water Reed, also known as Norfolk Reed or simply Thatch Reed is a type of wetland grass that has been used in thatching for thousands of years. It was originally common on properties around the Norfolk area of England, close to where the grass naturally grew. However, you’ll often find this material in use on thatched roofs across the country as popularity with thatchers has increased over the recent decades.
Water Reed is the predominant thatching material used in countries such as Germany and the Netherlands, where you’ll rarely see alternative materials being used.
Thatch made up of Water Reed should last from 25 to 40 years if cared for properly.
Combed Wheat Reed
Also referred to as Devon Reed, Wheat Straw or simply Wheat Reed, this material is often used as a ridging material. The material is made from wheat straw which has been combed to remove smaller straws and leaves as opposed to threshing which consists of beating the material to separate the grain from the straw. The result is a strong straw which provides a clean, crisp finish, hence its widespread use in ridging, although it’s not uncommon to see entire roofs thatched with Combed Wheat Reed.
Thatch made up of Combed Wheat read should last from 25 to 35 years if cared for properly.
Long Straw
Long Straw used to be the most popular material for thatching, but now sits in third place behind Water Reed and Combed Wheat Reed. Made from straw specifically grown for thatching, it’s similar to its combed counterpart although it is threshed to remove the smaller straws and leaves as opposed to combing. Long Straw work is generally more labour intensive which commands a higher price, that paired with its relatively low lifespan when compared to Combed Wheat Reed means it’s rarely chosen for new builds.
Thatch made up of Long Straw typically lasts for 15 to 25 years.
2. Quality of Materials
In addition to the materials themselves, it’s important to recognise the importance of the quality of the materials. In addition to growing, the materials themselves must also go through a series of processes before being made suitable for use on a roof. The processeses differ depending on the specific material, but it generally consists of cutting, binding, ripening, threshing or combing and then bundling. These processes can have a large impact on the final quality of material long before it’s to be installed on a roof.
The manner in which the materials are stored and their age can also have a large impact on the overall material quality; If thatch has been inadequately stored it can absorb excessive amounts of water which can lead to mould or fungus growth which may compromise the integrity of the thatch. Similarly, if that has been stored for an excessive period of time or it has been exposed to the elements for too long, it may become brittle.
As you can see, there’s a lot that goes goes into determining the final quality of thatch materials, so it’s important that any work on a thatched roof is carried out by reputable Master Thatcher, especially if you’re hoping to get another few decades of use out of it! It’s also important to look through any property history relating to the roof if you’re considering buying a thatched property, or if you already own and are considering any work on your thatched property.
3. Roof Pitch
Some people may be surprised to learn that the pitch of the roof can play a large role in how long a thatch roof may last. The pitch is directly related to the rate of which moisture runs off of the roof; a shallow pitch will allow moisture to remain on the surface for a longer period of time when compared to a steeper pitch. Pair a shallow pitch with a sheltered, maybe North-facing elevation and you might have a recipe for a roof that holds onto a lot of moisture, at least on one side of the building.
However, steep elevations aren’t completely in the clear either; having a steep pitch could mean the roof is more susceptible to wind damage as those gusts have a larger surface area to run into.
Above points aside, these concepts must be taken into consideration whilst looking at a number of different factors that we’ll highlight throughout this guide. Just because you have a shallow pitch on your roof doesn’t mean that it’s is going to leak or rot, and having a steep roof pitch doesn’t mean the thatch is going to get damaged or blow away any time soon.
4. The Surrounding Environment
The surrounding environment can have a large effect on how long a thatched roof will last. If you consider a house surrounded by large trees, it’s easy to imagine how those trees might block sunlight from hitting the roof, which could lead up to a buildup of moisture in the roof itself. Also consider how vegetation such as leaves may fall in the Autumn and settle on the roof, which could also increase the moisture levels but also begin to decompose and lead to other organic matter growing in the thatch. This is the reason Master Thatchers often advise to keep thatched roofs clear of vegetation and obstacles that could pose a problem.
The property should be looked at as a whole, identify issues with the surrounding environment and use that alongside other pointers we mention in this guide such as the Roof Pitch to get an understanding of how long your thatched roof will last.
5. Pollutants
It’s unlikely that pollutants and their effects on thatch were an issue when the thatched roofing method was pioneered all those centuries ago, but in these modern times, they can play a large role in how long a thatched roof will last. Modern pollutants found in petrol and diesel fumes can cause thatch to deteriorate at a faster rate and as such, thatched roofs in more metropolitan areas tend to need attention more often than those in more rural locations.
While there’s not much you can do about the location of a property, it’s always good to bear this in mind when considering purchasing a thatched property.
6. Birds, Mice and Other Pests
Humans aren’t the only creatures to recognise the benefits in using straw and grasses as building materials; Birds, mice and other pests are sometimes very keen to move in and share your lovely thatched roof with you. Whatever your stance when it comes to these critters, the damage they can do to thatched roofs can range from a minor annoyance, to a serious financial pain if left unaddressed. With this in mind, always keep an eye on what’s going on with your roof, check to see if you can notice anything scurrying about or increased bird activity. Master Thatchers generally recommend installing netting on roofs that are prone to problems with birds or rodents.
7. Breathability
Generally speaking, thatched roofs are very good at letting air circulate around the attic space and between the layers of the thatch itself. However, if the roof becomes swamped with debris from nearby trees as mentioned in our The Surrounding Environment section or if any work has been done that may increase the moisture levels in and around the roof, you will need to address them in order to ensure the longevity of the thatched roof. As a general rule of thumb, anything that will increase moisture levels in or around the thatch should be avoided or specifically addressed if there’s absolutely no alternative.
8. Damage
Thatch is happiest when it’s left undisturbed, the materials packed together provide an excellent seal from the elements. However, when disturbed, you’ll find that certain areas of thatch start coming away from the roof and provide an excellent starting point for bigger issues further down the line. Therefore, it’s a good idea to prevent people such as tradesmen who may be unfamiliar with thatched roofs from walking (and certainly working on) the thatch. This also applies to people that may be working close to, but not on the roof itself, for example a Tree Surgeon trimming overhanging tree branches or a tradesperson tasked with repairing a chimney.
There’s no reason a thatched roof can’t last for many years if looked after correctly, if you notice any damage developing in the thatch, whether that be from humans or by wildlife as mentioned in our Birds, Mice and Other Pests section, it’s important that you consult a reputable Master Thatcher so they can evaluate the damage and advise on how to best repair the roof.
9. The Weather
Mother nature is always beating down on the roof, whether it be rain or shine, the natural elements are constantly affecting the roof and will always be a key decider on how long a thatched roof will last. The number one factor out of all of the elements is moisture, you may notice we’ve mentioned this a number of times in this guide, namely in our Surrounding Environment, Roof Pitch, and Breathability sections, but excessive moisture can cause the organic matter that makes up the thatch to break down more quickly. This is why thatch in warmer, more humid environments doesn’t tend to last as long as those in cooler, drier climates.
Sunlight and wind also have their part to play in affecting how long a thatched roof will last, excessive sunlight can cause thatch to become brittle and high winds can also cause thatch to break away from the roof if it becomes loose. With these points in mind, along with the other points mentioned in this guide, have a look at the weather in the local area to get an idea of how long your thatched roof might last.
10. Quality of Workmanship
This is probably one, if not the most important point out of the entire guide – it’s absolutely paramount that a reputable Master Thatcher is used for any works on a thatched roof. Master Thatchers are skilled craftspeople that have spent years learning the trade and will be able to advise you on the best course of action based on your current circumstances and work that needs to be done. Employing someone who isn’t sufficiently qualified to carry out the work may lead to them damaging the roof, not providing an adequate finish and may end up costing you much more in the long run.
If you’ve recently bought a thatched property, or are looking to buy a thatched property, locate or request records about past works on the roof and see who has carried out the work, are they a registered Master Thatcher? How many different people and/or companies have worked on the roof? How much has been spent on the roof and how often? Asking these questions should help you to discover whether there’s a long-established history of issues with the roof and what sort of care and attention has been paid to it in the past.